1. Field of Invention
This invention relates to a motorized motor vehicle component with a drive having a motor and gearing and with a component which can be moved by means of the drive, the gearing having a drive side and a driven side, the motor being coupled to the driving side of the gearing and the driven side of the gearing being coupled to the movable component, the kinematic chain of the gearing, between the driving side and the driven side, having at least two transmission elements and the drive being operable in a blocking operation, and for this reason, an displaceable blocking element is movable into blocking engagement with the drive.
Here, the expression “motorized motor vehicle component” encompasses all those components of a motor vehicle which provide functions which can be triggered by a motor. Examples of functions which can be triggered by a motor include the central locking system, opening aid, closing aid or the mechanical redundancy of a motor vehicle door lock. Furthermore, motorized motor vehicle components from other areas are also encompassed, such as, for example, the motorized actuating means of the hatch, door or sliding door, the motorized seat or seat height adjustment, or the motorized window raiser of a motor vehicle.
2. Description of Related Art
All motorized motor vehicle components have some kind of drive for executing the function which can be triggered by a motor—therefore for actuation of an adjustable component—, the drive in turn being composed, in any case, of a motor and gearing which is connected downstream of the motor.
It is important for reliable operation of the motorized motor vehicle component that the motor with the corresponding control of motion starts the mechanical states of the drive which are required at the time as reliably as possible.
In the case of an electric motor, one possibility for controlling motion involves short-circuiting the motor briefly before reaching the desired position—dynamic braking. The disadvantage in this approach is that, generally, sensors for determining the prevailing motor position are necessary and that reliability is subject to major fluctuations depending on the respective temperature.
Another possibility is to allow the drive to run against a stop when the desired position has been reached, so that the motor, after a predetermined time interval, or after detection of an overcurrent, can be turned off by the coordinating control—blocking operation.
The known motor vehicle component which underlies this invention (U.S. Pat. No. 5,938,253) shows one possible implementation of the above described blocking operation using a motorized opening aid function for a motor vehicle door lock. In this case, the motor vehicle door lock has a latch and a ratchet which keeps the latch in the closed position, and the ratchet can be raised by means of a drive into the position which releases the latch. For this purpose, the drive has an actuating element with a driver pin which presses the ratchet into its raised position in an actuating process. Toward the end of the actuating process, the driver pin engages the ratchet such that the motor of the drive is blocked by the ratchet, the motor current rises measurably and after a certain delay time, the motor is turned off. Here, the ratchet, therefore the adjustable component, with motion which is to be controlled by the drive, itself, forms an displaceable blocking element which is necessary for blocking operation. This fact alone leads to undesirable structural limitations in the implementation of the ratchet. It is especially disadvantageous in this respect if it is considered that, for the required high raising speeds of the ratchet, what is important is especially the optimum matching between the reset spring force which acts on the ratchet and the ratchet weight as well as the corresponding weight distribution. However, these structural boundary conditions are disadvantageous also with respect to the continuing demand to increase compactness of motorized motor vehicle components.
Finally the known construction is disadvantageous in that the high blocking force or the high blocking moment leads to undesirable striking noise which is generally considered to be disturbing. Furthermore, the high blocking force leads to the material of the actuating element and the ratchet, as well as the corresponding gears, having to be made especially rigid. This imposes a further undesirable structural limitation.